What will a STi Exhaust do for a WRX?

**memo's wrx** · 11-07-2003 09:02 PM

Will installing a rear pipe and muffler off of a STi give any performance increase?

How much more would a STi turbo back system offer?

Is it worth the time to swap?

Thanks Bill

**Mattr762** · 11-07-2003 09:30 PM

There is very little to no advantange to swapping out for the STi turbo-back. It still has 2 cats and is 2.25" in diameter just like the WRX.

**tubbytreats** · 11-07-2003 09:54 PM

Just a side note:

The STI uppipe is catless, so if you get your hands on that, you will get a performance increase over your stock WRX.

The 2.25" pipe isn't really a huge problem power wise (until you are pushing 300 BHP or more), but the 2 remaining cats certainly restrict alot of the power potential for the car.

Catless downpipe and uppipe are your best bet.

**KurleeDaddeeWRX** · 11-07-2003 11:36 PM

So did you get it installed or not? I don't just post and try to help out for nothing. Please post how your install turned out, and did you figure out your o-ring problem?

**memo's wrx** · 11-08-2003 10:37 AM

Any recomadations on a system that won't make my car too loud, but still offer a performance gain with breaking the bank?

**Mattr762** · 11-08-2003 10:50 AM

Couple of things reduce the volume of high performance exhaust.
1. Cats (preferably get a 3" high flow cat)
2. Muffler (Prodrive, Borla Hush and GReddy cat-backs are known for being much quieter than most.
3. Resonator (either before the muffler or built within the tail-pipe)
4. Diameter of pipe (3.5" will be much louder than 2.5")

Of course if you don't want to break the bank then I recommend having a local muffler shop building one for you. I built an entire turbo-back for $400 Seen here.

**WRX** · 11-08-2003 12:48 PM

sorry to hijack the thread, but is there a return hose that's supposed to go from the BOV to the turbo inlet? I'm asking for a friend.

**Shibby** · 11-08-2003 12:59 PM

Originally posted by KurleeDaddeeWRX
So did you get it installed or not? I don't just post and try to help out for nothing. Please post how your install turned out, and did you figure out your o-ring problem?

yeah, i installed it just fine. Your advice helped, the O-ring fits around the return piece real snug. It went fine.

**hatebobbarker** · 11-08-2003 01:29 PM

just get an exhaust that has a silencer available

**grantn** · 11-12-2003 07:27 PM

I just bought a blitz FMIC and I was wondering if I could use the AVO BOV that was used on a TMIC? Also where can I buy a flange for the BOV?

ThanX

**Shibby** · 11-15-2003 08:58 PM

I plan to use my OEM BOV for Cobb's stage 2. Will the OEM be able to hold the increased boost. Will it still perform well?

**Chunks** · 11-15-2003 09:27 PM

yes, stock bov is adequate for pretty much anything under 20 psi or so.

**AjIsDope** · 11-15-2003 09:31 PM

What he said. ^^^

**Racenut** · 11-16-2003 10:12 AM

I have Cobb Stage 2 and stock BOV. Holds boost and works just fine. The boost increase is only a little more than 1psi.. though I do occasionally get up to 17psi if the weather is just right. I'm at sea level though, I guess that helps too.